The present disclosure relates to methods and apparatuses for forming thin microelectronic dies.
Existing microelectronic device packages typically include a microelectronic die attached to a support member, such as a printed circuit board. Bond pads or other terminals on the die are electrically connected to corresponding terminals on the support member, for example, with solder balls or wires. The connection between the die and the support member can be protected by encapsulating the die, forming a device package. The package can then be electrically connected to other microelectronic devices or circuits, for example, in a consumer or industrial electronic product such as a computer.
Electronic product manufacturers are under continual pressure from end users to reduce the size of the products they make. Accordingly, microelectronic die manufacturers are under pressure to reduce the size of the packaged dies incorporated into the electronic products. One approach to reducing the size of the packaged dies is to reduce the thickness of the dies themselves, for example, by grinding the backside of the wafer from which the die is singulated or diced. One drawback with this approach is that the thin wafer is extremely fragile and is therefore difficult to handle without damaging or breaking it. One approach for addressing this drawback is to attach a relatively thick wafer support to the wafer during the grinding process. The wafer support is then removed after grinding, for example, by heating the bond between the wafer and the wafer support, or by dissolving the bond with an acid. The resulting thin wafer is then attached to a dicing frame with an adhesive. The wafer is singulated or diced into individual dies while it is attached to the dicing frame. After the dicing operation, the adhesive is exposed to ultraviolet radiation which reduces its adhesive strength and allows the dies to be removed from the frame and packaged.
One drawback with the foregoing approach is that the wafer support is removed prior to dicing the wafer. Accordingly, the wafer can be vulnerable to damage and/or breakage until it is supported by the dicing frame. A further drawback of the foregoing approach is that the individual dies may be subject to damage and/or breakage from the time they are removed from the dicing frame to the time they are encapsulated. Accordingly, the foregoing process can be inefficient and expensive because it can damage individual dies and/or entire wafers, which must then be replaced.
The present invention is directed toward methods and apparatuses for forming thin microelectronic dies. A method in accordance with one aspect of the invention includes releasably attaching a microelectronic substrate to a support member with an attachment device. The microelectronic substrate can have a first surface, a second surface facing opposite from the first surface, and a first thickness between the first and second surfaces. The attachment device can have a releasable bond with the microelectronic substrate, the releasable bond having a bond strength that is reduced upon exposure to at least one energy. The support member can be at least partially transmissive to the at least one energy. The method can further include reducing a thickness of the microelectronic substrate from the first thickness to a second thickness while the microelectronic substrate is releasably attached to the support member. A quantity of the at least one energy can be directed through the support member to the attachment device to reduce the strength of the bond between the attachment device and the microelectronic substrate. At least a portion of the microelectronic substrate can be separated from the support member.
A method in accordance with another aspect of the invention includes attaching the first surface of the microelectronic substrate to a generally rigid support member, wherein the microelectronic substrate includes first and second microelectronic dies each having at least one circuit element at least proximate to the first surface. The method can further include separating a first portion of the support member adjacent to the first microelectronic die from a second portion of the support member adjacent to the second microelectronic die while the first microelectronic die is releasably attached to the first portion of the support member and the second microelectronic die is releasably attached to the second portion of the support member. The first and second microelectronic dies can be separated from each other while the first microelectronic die is releasably attached to the first portion of the support member and the second microelectronic die is releasably attached to the second portion of the support member. The first microelectronic die can then be separated from the first portion of the support member and the second microelectronic die can be separated from the second portion of the support member.
A method in accordance with still another aspect of the invention includes attaching the first surface of the microelectronic substrate to a generally rigid support member, separating the first microelectronic die and a corresponding first portion of the support member from the second microelectronic die and a corresponding second portion of the support member, and adhesively attaching the first microelectronic die and the first portion of the support member as a unit to a die attach member. The method can further include solidifying a bond between the first microelectronic die and the die attach member while simultaneously reducing the strength of a bond between the first microelectronic die and the first portion of the support member. The first portion of the support member can be separated from the first microelectronic die and the first microelectronic die can be electrically coupled to the die attach member.
The invention is also directed to a microelectronic assembly. In one aspect of the invention, the microelectronic assembly includes a microelectronic substrate having a first surface and a second surface facing opposite from the first surface. The microelectronic substrate can further include a first die and a second die, with each of the first and second dies having at least one circuit element positioned at least proximate to the first surface of the substrate. A first processing support member is positioned proximate to the first surface of the microelectronic substrate and is at least partially transmissive to at least one energy. A first attachment device is disposed between the microelectronic substrate and the first processing support member and includes an adhesive bonded to the support member with the adhesive having a reduced adhesiveness upon exposure to the at least one energy. A second processing support member can be positioned proximate to the second surface of the microelectronic substrate, and a second attachment device can be releasably disposed between the microelectronic substrate and the second processing support member.